Brigham Young declares war on Timpanogos in the Battle at Fort Utah.

The Battle at Fort Utah (also known as Fort Utah War or Provo War) was a battle between the Timpanogos Tribe and remnants of the Nauvoo Legion at Fort Utah in modern-day Provo, Utah. The Timpanogos people initially tolerated the presence of the settlers, and the two groups enjoyed some moments of mutual friendship. However, after three Mormons murdered a Timpanogos man called Old Bishop and a hard winter where Timpanogos took around 50 Mormon cattle, settlers in Fort Utah petitioned to go to war with the Timpanogos. Isaac Higbee, Parley P. Pratt and Willard Richards convinced Brigham Young to exterminate any Timpanogos hostile to the Mormon settlement. Young sent the Nauvoo Legion down with Captain George D. Grant and later sent General Daniel H. Wells to lead the army. After the Timpanogos defended themselves from their village and an abandoned cabin, they fled their camp. The Mormons pursued the Timpanogos from Chief Old Elk's tribe and any other Timpanogos they found in the valley, killing Timpanogos from Chief Pareyarts or Para-yah (Old Elk)'s tribe and other tribes even if they had no history of attacking the Mormons. The Nauvoo Legion killed around 100 Timpanogos.

Brigham Young (; June 1, 1801 – August 29, 1877) was an American religious leader and politician. He was the second president of The Church of Jesus Christ of Latter-day Saints (LDS Church) from 1847 until his death in 1877. During his time as church president, Young led his followers, the Mormon pioneers, west from Nauvoo, Illinois to the Salt Lake Valley. He founded Salt Lake City and served as the first governor of the Utah Territory. Young also worked to establish the learning institutions which would later become the University of Utah and Brigham Young University. A polygamist, Young had at least 55 wives and 56 children. He instituted a ban prohibiting conferring the priesthood on men of black African descent, and led the church in the Utah War against the United States.